How protesters uncovered hoodie from Scotland Yard

The policeman is confronted by protesters after his attempt to infiltrate their ranks was discovered

An undercover policeman was unmasked by anti-capitalist protesters after he tried to infiltrate the group as they stormed the London base of a FTSE 100 firm.

The moment when the hoodie-wearing officer was identified by members of the Occupy London movement during their protest outside the office of mining firm Xstrata was captured on video.

Protesters asked the man whether he worked for the Metropolitan Police. He can be seen in the film nodding and answering: "Yeah, I'm a Met Police officer, yeah."

Activists then surrounded the officer, chanting "shame on you" and "scum, scum, scum", before he was allowed to reach the line of uniformed police who were kettling the protest. The attempted raid on the building near Piccadilly Circus came during protests in London on Wednesday.

A Met spokesman said the undercover officers were on hand to "identify those who had committed crimes so they could make arrests".